There is known a blood bag system for centrifugal separation of whole blood collected from a donor into three kinds of blood cell products for blood transfusion, which include concentrated red blood cell (CRC), platelet concentrated (PC), and platelet-poor plasma (PPP).
Such blood cell products for blood transfusion often undergo, after separation and storage, a process of removing white blood cells immediately before transfusion into a patient in order to avoid side effects induced after blood transfusion by contamination with white blood cells.
However, it is known that blood obtained by blood donation gives high-quality blood cell products for blood transfusion if it is freed of white blood cells before separation and storage. In order to remove white blood cells before blood separation and storage, there has been developed a leukocyte removing filter system (in-line filter) consisting of a blood bag system and a filter which are integrally connected to each other. (See Patent Document 1 below.)
However, the system disclosed in Patent Document 1 has the following disadvantages.
First, the in-line filter is inconvenient to handle and makes the system bulky as a whole, although it functions as a constituent of the closed system in which the circuit, filter, and bag are so connected as to permit aseptic blood treatment.
Second, the system has to be discarded together with an intact in-line filter when collected blood is judged to be inadequate for blood products for quantitative or qualitative reasons and hence is discarded. This wastes the in-line filter.
Third, the system does not permit blood separation and storage without removal of white blood cells even in the case where it is not necessary to remove white blood cells to make collected blood into blood products for blood transfusion.
Fourth, the system needs moist heat sterilization (in an autoclave) because the bag contains anticoagulant, blood preservative, etc. This moist heat sterilization could deteriorate the filter medium of the in-line filter connected to the bag, thereby decreasing the efficiency of leukocyte removal, in the case where the material used for filtration is not resistant to moist heat sterilization.
In order to overcome the above-mentioned disadvantages, there has been proposed a new system in which a filter and recovered bag (a recovered bag with a filter) is separated from the blood bag system. In this new system, a collected blood bag of the blood bag system is connected to the recovered bag with a filter by a connector when removal of white blood cells is required. (See Patent Document 2 below.)
However, the system proposed in Patent Document 2 needs two code numbers for one donor because the tube carried different segment numbers for the blood bag system and the recovered blood bag with the filter. This results in complicated management.
Patent Document 1:
Japanese Patent Publication No. 6-59304.
Patent Document 2:
Japanese Patent No. 2,952,433